Haha ~ I love how people are in denial.
Let's see,
Matsuri has the sword.
Since she asked Takeshi how to use it we can presume she doesn't know anything more about it then we do; namely, the sword nullifies Yaka powers. Since it requires training to use, apparently, we can presume she's not just going to hand it to Aono.
Matsuri has the following options:
She can stab herself, but that's not going to happen, I mean can't she stab herself in private, what would be the point to have Aono or Yorito there.
She can stab Yorito ~ but then what would be the point ~ he's pretty resilient, at that pace Aono would die at the same time. Why be cruel and not put her out of her misery in advance for Yorito's. But there's also another more simple reason. Why stab Yorito facing Aono.
And the last option. Stab Aono. This is probably the only option which would call for a face off.
In my opinion Matsuri wants to kill Aono to break some sort of curse. Remember Aono was a sacrifice to the gods. She's late for her meeting I would think. I hope we FINNALY get to hear the thing that she's been sobbing about. I know everyone is thinking of her as a some bucket of joy but from all her lines all I get is: "I did something bad, so now I have to be extra nice to the world." I call bets on Matsuri being some old childhood friend of Aono who backstabed her somehow ~ maybe she was the sacrifice originally..
Well, to me Matsuri's latest development doesn't look at all out of character. I mean remember when they both went primal-mode, Matsuri's face showed anger while Aono's showed sadness.
The thing I really love about this episode is that we finally get some solid proof that Aono's fears and reckless behaviour in earlier episodes when concerning Matsuri-events were justified ~ and she's not demon plotting behind people's backs! HA!
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One more thing, what is this Happy Ending you all speak of ~ do you people understand they are ghosts, actually ghosts of the material world, phantoms, or perhaps closer to zombies. The "happy ending" is the triple suicide theory were they all go to heaven to eat cake T_T Actually for your happy ending Mana and Kayori would either need to commit suicide and either go to heaven to join them, presuming earlier theory, or become yaka's themselves and live in trashcans watching the sky for the rest of eternity.
I can accept any ending accept a ending were mystery phenomenon is revealed and everyone uses some plot dues ex machina to become human
or some cruel ending in happy ending clothing.